A suction roll used for dewatering of sheeting e.g. for paper machines comprises a roll shell with openings and disposed within at least one suction box. The suction box is arranged stationary on the inside of the suction roll with the holey roll shell rotating around the suction box. To seal the suction box from the roll shell, said roll shell comprises lateral sealing strips which seal the inside of the suction box from the remaining volume of the suction roll, preferably in longitudinal direction of the suction roll. The suction box is delimited on both ends in peripheral direction of the suction roll by edge deckles and sealed from the roll shell.
Specific problems during construction and/or operation of suction rolls consist in the abrasion of sealing strips and the generation of noise near the sealing strips.
EP0943729 B1 discloses a sealing strip, which is pressed against the inner wall of the suction roll by a load element in form of a pressure hose when the vacuum is created within the suction box.
During operation, the sealing strip is pushed away somewhat from the inner wall of the suction roll by a resetting element, which is provided as well in form of a pressure hose, this leads to a defined, adjustable sealing gap. It is intended for noise reduction that the gap between the sealing strip and the inner wall in peripheral direction widens gradually.
The EP1348805 B1 has disclosed the implementation of a sealing strip with adjustable sealing gap with the adjustment of the gap via a vertically adjustable strip by a pressure hose, which are hingedly connected to the rear end of the sealing strip.
The EP1344865 B1 shows a suction roll in which a microphone is installed on the inside of the suction roll in the area of the rear sealing strip of the suction box. If the measured sound level exceeds a certain threshold, countermeasures are being implemented which can consist of the adjustment of the gap between the sealing strip to the inner wall and/or the adjustment of the opening angle of the strip between suction strip and inner wall.
DE102007027688 A1 discloses the integration of several temperature sensors into the sealing strip, which are assembled along the longitudinal direction of the sealing strip, i.e. transverse direction of the paper machine. Once the threshold temperature has been reached, the gap between the sealing strip and the roll shell is increased. It is assumed additionally that the negative pressure inside the suction box will be monitored. If the negative pressure decreases, the sealing strip is moved back again into the direction of the inner wall. Subsequently, the gap and/or the contact pressure and/or advancing pressure of the sealing strip in the area between the threshold value of the temperature and the threshold value of the pressure drop will be regulated. Adversely, it can lead to a slow or failed adjustment and/or if a threshold value cannot be achieved without ignoring the second threshold value, no appropriate countermeasures can be implemented.
WO2013174573 A1 discloses in the sealing strip the provision of several electrical conductors in form of a ribbon cable, which extends over the entire length of the sealing strip in order to monitor the abrasion of the sealing strip. The individual conductors are embedded in varying depths into the sealing strip, thus said conductors are consecutively cut after abrasion of the sealing strip. Adversely, only the maximum value of abrasion is known and an uneven abrasion of the sealing strip stays undetectable.
DE102005048054 A1 discloses the regulation of the advancing pressure of the control device of the sealing strip in such a way, that the entire contact pressure remains consistent. The entire contact pressure is comprised of the advancing pressure of the control device of the sealing strip and an element produced by the vacuum inside of the suction box, said element acts through the openings of the suction roll upon the sealing strip.
Adversely, the state of the art provides no satisfactory overall concept for the failsafe, low noise and low resource operation of a suction roll.